the gastric cancer in iran is the fourth in the general population. this study was designed to determine the five-year survival rate of gastric cancer patients, and to assess its associated factors. we analyzed the data using a time-dependent covariates model, and recommend it for analyses of similar data. 281 gastric cancer patients with adenocarcinomatous pathology who had been operated on at...

background: in survival studies when the event times are dependent, performing of the analysis by using of methods based on independent assumption, leads to biased. in this paper, using copula function and considering the dependence structure between the event times, a parametric joint distribution has made fitting to the events, and the effective factors on each of these events would be determ...

this paper deals with a delayed ratio-dependent functional response predator-prey model with a threshold harvesting policy. we study the equilibria of the system before and after the threshold. we show that the threshold harvesting can improve the undesirable behavior such as nonexistence of interior equilibria. the global analysis of the model as well as boundedness and permanence properties a...

We study the asymptotic behaviour of an ecological model in presence a time dependent birth rate.

In this paper, we considered a deterministic inventory model with time-dependent demand and time-varying holding cost where deterioration is time proportional. The model considered here allows for shortages, and the demand is partially backlogged. The model is solved analytically by minimizing the total inventory cost. The result is illustrated with numerical example for the model. The model ca...